Process for the preparation of fluticasone propionate form i

ABSTRACT

The invention relates to a novel crystallisation process for preparing fluticasone propionate as crystalline form 1 polymorph with controlled particle size and suitable for micronisation. Said process comprises the step of dissolving fluticasone propionate in acetone or in a mixture of acetone and water and then adding this solution to water or to a mixture of water  10  and acetone, thereby causing fluticasone propionate to crystallise out of the solution as crystalline form.

The present invention relates to a novel crystallisation process forpreparing fluticasone propionate as crystalline form 1 polymorph withcontrolled particle size and suitable for micronisation.

Fluticasone propionate is a corticosteroid acting as a potentanti-inflammatory and which is used as crystalline form 1 in thetreatment of rhinitis, eczema, psoriasis, asthma and COPD. It has thechemical nameS-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carbothioate,17-propionate and the following chemical structure:

Several processes for preparing fluticasone propionate, in particular asits stable crystalline form 1, have been described in the literature.For example, WO 00/38811 discloses the crystallisation of fluticasonepropionate dissolved in acetone by mixing with water in the presence ofultrasound radiation. WO 01/32125 discloses the crystallisation offluticasone propionate by admitting a stream of solution of fluticasonepropionate in acetone and a stream of water as anti-solvent tangentiallyinto a cylindrical mixing chamber having an axial outlet port such thatsaid streams are intimately mixed through formation of a vortex.However, these processes are not easily scalable and use complexapparatus and technologies (such as use of ultrasound).

Other, more simple, crystallisation processes have also been proposed.For example, the so-called crystalline form 1 of fluticasone propionatecan be obtained by dissolving the crude product as obtained in e.g. GB2088877 in ethyl acetate and then re-crystallising. Alternatively, amethod for preparing fluticasone propionate as crystalline polymorphicform 1 by mixing a solution of fluticasone propionate in a non-solvatingorganic liquid solvent such as methyl acetate, ethyl acetate orpentanone, with a non-solvating organic liquid anti-solvent such astoluene, isooctane or hexane thereby causing fluticasone propionate ascrystalline form 1 to crystallise out of the solution has been describedin WO 03/066653. However, it has been found that these crystallisationprocesses do not offer control and flexibility in terms of outputparticle size distribution for fluticasone propionate. Similar to themajority of drugs intended for delivery to the lung, fluticasonepropionate is usually subjected to micronisation prior to formulation toenable production of appropriately sized respirable particles. It ishowever well known from the literature that there is a link between theparticle size of ingoing material and the size of micronized product,hence it is of key importance to precisely control the particle size ofthe material that is fed into the microniser to ensure reliable andeffective drug delivery to the lung.

The present invention represents a solution to the above mentionedproblems. The present invention is indeed directed to a newcrystallisation process for preparing fluticasone propionate ascrystalline form 1 which is scalable, reproducible and does not involvecomplex apparatus. The crystallisation process according to the presentinvention also enables more flexibility and precise control of productparticle size distribution through variations in solvent composition.Finally the crystallisation process according to the present inventionshows lower product loss in the micronisation chamber compared to atraditional anti-solvent crystallisation.

The present invention is thus directed to a process for preparingfluticasone propionate as crystalline form 1, which comprises the stepof dissolving fluticasone propionate in acetone or in a mixture ofacetone and water and then adding this solution to water or to a mixtureof water and acetone, thereby causing fluticasone propionate tocrystallise out of the solution as crystalline form 1.

According to the present invention, the water or water/acetone mixturein which the fluticasone propionate solution is added may also bereferred as the “non-solvent” or the “non-solvating mixture”respectively.

According to an embodiment, fluticasone propionate is dissolved inacetone containing 0 to 10% water, and the resulting solution is addedto water containing 0 to 35% acetone. Preferably, fluticasone propionateis dissolved in acetone, and the resulting solution is added to watercontaining 0 to 30% acetone.

According to another embodiment, a solution is prepared throughdissolving fluticasone propionate in acetone or an acetone/water mixturewith concentrations between 30 and 50 grams per litre of solvent.Preferably, said solution is prepared through dissolving fluticasonepropionate in acetone or an acetone/water mixture with concentrationsbetween 35 and 45 grams per litre of solvent.

According to a further embodiment, fluticasone propionate is dissolvedin 1 volume of acetone or acetone/water mixture and this solution isthen added to a volume of water or water/acetone mixture comprisedbetween 0.65 and 1.35. Preferably, 1 volume of the fluticasonepropionate solution is added to a volume of water or water/acetonemixture comprised between 0.8 and 1.2. More preferably, 1 volume of theacetone/fluticasone propionate solution is added to a volume of water orwater/acetone mixture of about 1.

According to another embodiment, the addition takes place at atemperature comprised between 10° C. and 40° C. Preferably, the additiontakes place at ambient temperature.

According to another embodiment, the addition takes place over a periodcomprised between 10 minutes and 6 hours. Preferably, the addition takesplace over a period comprised between 30 minutes and 2 hours. Morepreferably, the addition takes place over a period of about 1 hour.

According to another embodiment, the addition of the fluticasonepropionate solution occurs via a pump in the form of pulsed aliquots.

During and following from the addition of the fluticasone propionatesolution into the non-solvent or non-solvating mixture, nucleation andgrowth of fluticasone propionate occur. Once the fluticasone propionatesolution addition into the non-solvent or non-solvating mixture iscompleted, the slurry formed is stirred over a period comprised between0 and 12 hours, followed by filtration and drying. Preferably, theslurry is stirred over a period of comprised between 1 hour and 10hours. More preferably, the slurry is stirred over a period comprisedbetween 4 hours and 8 hours. Still more preferably, the slurry isstirred over a period of about 1 hour.

The process according to the present invention is particularlyadvantageous since it allows good flexibility and control of thephysical properties of the fluticasone propionate obtained, inparticular the size and shape of the particles obtained. This isexemplified in FIG. 1, showing the dependence of particle size onsolvent composition when fluticasone propionate is crystallised usingthe process described in the present invention. Surprisingly, it hasbeen found that the specific reverse anti-solvent crystallizationprocess according to the present invention allows the crystallization offluticasone propionate with different particle sizes through variationsin solvent composition and also delivers fluticasone propionateparticles which do not exhibit the agglomeration which is typical ofconventional anti-solvent crystallization, as described for example byMumane et al. in Cryst. Growth Des. 2008, 8, 2753-2764 and asillustrated in FIG. 2.

In addition to influencing the efficacious delivery of intra-nasal andpulmonary drug formulations, control of physical properties offluticasone propionate is also important since these propertiesinfluence bulk density, flow and downstream processing characteristicsof the product.

Typically, the process according to the present invention yieldsparticles that are 5-200 μm in length with a width of 3-30 μm. Thefluticasone propionate particles obtained by the process according tothe present invention thus have the most appropriate design, inparticular for micronisation and formulation with lactose as a drypowder and administration with a dry powder inhaler such as the devicedescribed in e.g. WO 2005/002654. The particles of fluticasonepropionate obtainable from the herein described crystallisation processthus constitute another object of the present invention.

An additional and significant advantage of the particles resulting fromthe process according to the present invention is the increased yield inmicronized fluticasone propionate due to lower loss of product in thejet milling chamber, compared to micronisation input obtained from aconventional anti-solvent process

Fluticasone propionate may be prepared according to any of the processesknown from the literature such as e.g the process described in GB2088877. Alternatively, fluticasone propionate is also commerciallyavailable for a number of suppliers, e.g. Hovione, Sterling or NewChem.

The particles of fluticasone propionate as obtained from thecrystallisation process according to the present invention may bemicronized to a controlled size and formulated with lactose so as toform a dry powder blend.

Fluticasone propionate as obtained from the process according to thepresent invention is particularly suitable for micronisation andadministration by inhalation from a dry powder inhaler. Typically, it isadministered in the form of a dry powder as a mixture with lactose.

To that effect, the particles of fluticasone propionate as obtained fromthe process according to the present invention are micronized by jetmiling, and subsequently blended with lactose. The lactose usedaccording to the present invention may be anhydrous or in the form ofthe monohydrate. Preferably, α-lactose monohydrate is used. The blendthus obtained is then suitable for filling into a dry powder inhaler.

The dosage unit is determined by a pre-filled capsule, blister or pocketor by a system that uses a gravimetrically fed dosing chamber. Units inaccordance with the invention are typically arranged to administer ametered dose or “puff” containing from 50 to 500 μg of fluticasonepropionate as obtained from the process according to the presentinvention. The overall daily dose will typically be in the range of 50μg to 2 mg which may be administered in a single dose or, more usually,as divided doses throughout the day.

The fluticasone propionate obtained from the process according to thepresent invention may be administered alone or in combination with oneor more other drugs. Suitable examples of other therapeutic agents whichmay be used in combination with fluticasone propionate include, but areby no means limited to β₂ agonists, preferably long-acting β₂ agonists,and M3 muscarinic antagonists, preferably long-acting M3 muscarinicantagonists.

Examples of suitable β₂ agonists include in particular salbutamol,terbutaline, bambuterol, fenoterol, salmeterol, formoterol, tulobuteroland their salts. Preferably the β₂ agonist is selected from salmeterolor formoterol and their salts. More preferably, the β₂ agonist issalmeterol xinafoate.

Examples of suitable M3 muscarinic antagonists include in particularipratropium, oxitropium, tiotropium and their salts. Preferably the M3muscarinic antagonist is tiotropium bromide.

According to a preferred embodiment, fluticasone propionate as obtainedfrom the process according to the present invention is administered byinhalation as a dry powder either alone or in combination withsalmeterol xinafoate.

The figures and examples below further illustrate the present invention.

FIGURES

FIG. 1 of 10: Effect of acetone % in the anti-solvent mixture on thevolume median diameter D[v, 0.5] for a reverse anti-solvent process.

FIG. 2 of 10: Crystals of fluticasone propionate obtained from example1.

FIG. 3 of 10: Crystals of fluticasone propionate obtained from example2.

FIG. 4 of 10: PXRD patterns for Example 2 product (top line) andreference fluticasone propionate form 1 pattern for comparison (bottomline).

FIG. 5 of 10: Crystals of fluticasone propionate obtained from example3.

FIG. 6 of 10: PXRD pattern for example 3 product (top line) andreference fluticasone propionate form 1 pattern for comparison (bottomline).

FIG. 7 of 10: Crystals of fluticasone propionate obtained from example4.

FIG. 8 of 10: PXRD pattern for example 4 product (top line) andreference fluticasone propionate form 1 pattern for comparison (bottomline).

FIG. 9 of 10: Crystals of fluticasone propionate obtained from example5.

FIG. 10 of 10: PXRD pattern for example 5 product (top line) andreference fluticasone propionate form 1 pattern for comparison (bottomline).

EXAMPLES Example 1: Re-Crystallisation of Fluticasone Propionate Using aStandard Anti-Solvent Process

1.0 g of fluticasone propionate[S-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-173carbothioate, 17-propionate] obtained from a commercial source was mixedwith 25 mL acetone. The mixture was heated to 40° C., and then cooled to20° C. 25 mL water was added to the solution at approximately 20° C.Crystallisation of the product was observed during the addition. Theslurry was filtered under vacuum, and the isolated solid was dried in anoven at 50° C. under 0.9 bar vacuum, yielding fluticasone propionateForm 1. Crystals obtained from this experiment are shown in FIG. 2.

Example 2: Re-Crystallisation of Fluticasone Propionate Using theReverse Anti-Solvent Process of the Present Invention

7.5 g of fluticasone propionate[S-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-173-carbothioate,17-propionate] obtained from a commercial source was mixed with 225 mLacetone. The mixture was heated to 40° C., and then cooled to 10° C. Thechilled solution was added to a separate agitated vessel containing 225mL water at 40° C. over a period of 10 minutes. Crystallisation of theproduct was observed during the addition. The mixture was cooled down to20° C. and held at that temperature for 12 hours. The slurry wasfiltered under vacuum, and the isolated solid was dried in an oven at50° C. under 0.9 bar vacuum, yielding 6.94 g of fluticasone propionate30 (92.4% theoretical yield).

Crystals obtained from this experiment are shown in FIG. 3.

Powder X-Ray Diffraction Data

The powder X-ray diffraction pattern was determined using a Bruker-AXSLtd. D4 powder X-ray diffractometer fitted with an automatic samplechanger, a theta-theta goniometer, automatic beam divergence slit, and aPSD Vantec-1 detector. The sample was prepared for analysis by mountingon a low background cavity silicon wafer specimen mount. The peaksobtained were aligned against a silicon reference standard. The specimenwas rotated whilst being irradiated with copper K-alphal X-rays(wavelength=1.5406 Angstroms) with the X-ray tube operated at 40 kV/35mA. The analyses were performed with the goniometer running incontinuous mode set for a 0.2 second count per 0.0180 step over a twotheta range of 20 to 550. Characteristic diffraction angles for the twoknown polymorphs of fluticaseon propionate, as reported in EU Patent EP0 937 100 B1, are as indicated below in table 1:

TABLE 1 Poly- Primary morph Peaks (°) Secondary peaks (°) Form 1 7.910.0 11.5 12.4 13.1 — 14.9 — 15.8 Form 2 7.6 9.8 — — 13.0 13.6 — 15.2 —

A PXRD pattern of the product obtained from this experiment, shown tomatch that of form 1 for fluticasone propionate, is shown in FIG. 4.

Example 3: Re-Crystallisation of Fluticasone Propionate Using theReverse Anti-Solvent Process of the Present Invention

10 g of fluticasone propionate[S-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carbothioate,17-propionate] obtained from a commercial source was mixed with 200 mLacetone. The mixture was heated to 40° C., and then cooled to 10° C. Thechilled solution was added to a separate agitated vessel containing 200mL water at 10° C. over a period of 10 minutes. Crystallisation of theproduct was observed during the addition. The mixture was heated to 20°C. and held at that temperature for 12 hours. The slurry was filteredunder vacuum, and the isolated solid was dried in an oven at 50° C.under 0.9 bar vacuum, yielding 9.33 g of fluticasone propionate (93.3%theoretical yield).

Crystals obtained from this experiment are shown in FIG. 5.

A PXRD pattern from the product, shown to match that of form 1 forfluticasone propionate, is shown in FIG. 6.

Example 4: Re-Crystallization of Fluticasone Propionate Using theReverse Anti-Solvent Process of the Present Invention

9 g of fluticasone propionate[S-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carbothioate,17-propionate] obtained from a commercial source was mixed with 270 mLacetone. The mixture was heated to 40° C., and then cooled to 10° C. Thechilled solution was added to a separate agitated vessel containing 175mL water and 75 mL acetone at 10° C. over a period of 6 hours.Crystallisation of the product was observed during the addition. Themixture was heated to 20° C. and held at that temperature for 12 hours.The slurry was filtered under vacuum, and the isolated solid was driedin an oven at 50° C. under 0.9 bar vacuum, yielding 8.56 g offluticasone propionate (95.1% theoretical yield).

Crystals obtained from this experiment are shown in FIG. 7.

A PXRD pattern from the product, shown to match that of form 1 forfluticasone propionate, is shown in FIG. 8.

Example 5: Re-Crystallization of Fluticasone Propionate Using theReverse Anti-Solvent Process of the Present Invention

9 g of fluticasone propionate[S-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carbothioate,17-propionate] obtained from a commercial source was mixed with 162 mLacetone and 18 mL water. The mixture was heated to 40° C., and thencooled to 10° C. The chilled solution was added to a separate agitatedvessel containing 270 mL water at 10° C. over a period of 6 hours.Crystallisation of the product was observed during the addition. Themixture was heated to 20° C. and filtered under vacuum.

i solid was dried in an oven at 50° C. under 0.9 bar vacuum, yielding7.56 of fluticasone propionate (84.0% theoretical yield).

Crystals obtained from this experiment are shown in FIG. 9.

A PXRD pattern from the product, shown to match that of form 1 forfluticasone propionate, is shown in FIG. 10.

Example 6: Re-Crystallisation of Fluticasone Propionate Using theReverse Anti-Solvent Process of the Present Invention

0.958 Kg of fluticasone propionate[S-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-17β-carbothioate,17-propionate] obtained from a commercial source was mixed with 24.7 Lacetone. The mixture was heated to 35° C., and then cooled to 20° C. Thesolution was added to a separate agitated vessel containing 24 L waterat 20° C. over a period of 2 hours. Crystallisation of the product wasobserved during the addition. The mixture was held at 20° C. for 1 hourwith agitation. The slurry was filtered under vacuum, and the isolatedsolid was dried in an oven at 75° C. under 0.9 bar vacuum, yielding 0.85Kg of fluticasone propionate (88.3% theoretical yield).

Example 7: Re-Crystallisation of Fluticasone Propionate Using theReverse Antisolvent Process of the Present Invention

2.50 Kg of fluticasone propionate[S-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-25methyl-3-oxoandrosta-1,4-diene-17β-carbothioate, 17-propionate] obtainedfrom a commercial source was mixed with 62.5 L acetone. The mixture washeated to 35° C., and then cooled to 20° C. The solution was added to aseparate agitated vessel containing 47 L water and 15.5 L acetone at 20°C. over a period of 2 hours. Crystallisation of the product was observedduring the addition. The mixture was held at 20° C. for 1 hour withagitation. The slurry was filtered under vacuum, and the isolated solidwas dried in an oven at 75° C. under 0.9 bar vacuum, yielding 2.26 Kg offluticasone propionate (90.4% theoretical yield).

Example 8: Re-Crystallisation of Fluticasone Propionate Using theReverse Anti-Solvent Process of the Present Invention

9.5 Kg of fluticasone propionate[S-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-173-carbothioate,17-propionate] obtained from a commercial source was mixed with 237.5 Lacetone. The mixture was heated to 35° C., and then cooled to 20° C. Thesolution was added to a separate agitated vessel containing 237.5 Lwater at 20° C. over a period of 4 hours. Crystallisation of the productwas observed during the addition. The mixture was held at 20° C. for 4hours with agitation. The slurry was filtered under vacuum, and theisolated solid was dried in an agitated dryer at 75° C. under 0.9 barvacuum, yielding 8.5 Kg of fluticasone propionate (89.2% theoreticalyield).

Example 9: Re-Crystallisation of Fluticasone Propionate Using theReverse Anti-Solvent Process of the Present Invention

2.50 Kg of fluticasone propionate[S-(fluoromethyl)-6α,9-difluoro-11β-17-dihydroxy-16α-methyl-3-oxoandrosta-1,4-diene-171-carbothioate,17-propionate] obtained from a commercial source was mixed with 56.25 Lacetone and 6.25 L water. The mixture was heated to 35° C., and thencooled to 20° C. The solution was added to a separate agitated vesselcontaining 40.6 L water and 21.9 L acetone at 20° C. over a period of 1hour. Crystallisation of the product was observed during the addition.The mixture was held at 20° C. for 1 hour with agitation. The slurry wasfiltered under vacuum, and the isolated solid was dried in an oven at75° C. under 0.9 bar vacuum, yielding 2.15 Kg of fluticasone propionate(86.0% theoretical yield).

Example 10: Particle Size Data as Measured by Laser Diffraction

The following particle size assays for crystallised and micronizedfluticasone propionate were used in this experiment:

Particle Size Method for Recrystallised FP:

The particle size distribution was measured on the Malvern Mastersizer2000 laser diffraction system equipped with a Hydro 2000S liquiddispersion unit and flow cell. The sample was prepared by adding 15drops of Tween 80 to crystallised fluticasone propionate within theglass 4 dram vial and mixing into a paste using a spatula, until all ofthe powder is wetted out and a smooth, uniform paste is achieved. Thenthe paste is added to the Hydro 2000S containing dispersant (0.1% Tween80 in deionised water) using a spatula. When the obscuration target isachieved (20%±5%) the sample is left to stir within the Hydro 2000S for1 minute to allow the particles to wet out, disperse and ensure a stableobscuration is achieved. Measurement is initiated after 1 minute ofstirring.

Particle Size Method for Micronised FP:

The particle size distribution was measured on the Sympatec HELOS laserdiffraction system (with R1 optical module giving a measuring range of0.1/0.18-35 μm) together with SUCELL dispersing module. 100 mg ofmicronised sample is weighed into a 4-dram vial and 15 drops(approximately 0.5 mL) of Tween 80 is added from a 3 ml wide-tippedpipette to the powder. The mixture is then carefully stirred into apaste until all the particles are wetted out and a uniform smoothmixture is achieved. Then the paste is added to the SUCELL containingdispersant (0.025% Tween 80 in deionised water) using a spatula. Oncethe optical concentration target is achieved (10-15%) then a measurementis taken.

The particle size data expressed as D[v, 0.1], D[v, 0.5] and D[v, 0.9]obtained from examples 2-9 are summarized below in Table 2. D[v, 0.1],D[v, 0.5] and D[v, 0.9] represent the 10^(th) percentile volumediameter; 50^(th) percentile volume diameter; and 90^(th) percentilevolume diameter respectively. In general the n^(th) percentile volumediameter is defined so that n % of the particles have a volumeequivalent particle diameter smaller than or equal to the n^(th)percentile diameter. In the case of D[v, 0.5], it coincides with themedian value.

TABLE 2 Batch D[v, 0.1] (μm) D[v, 0.5] (μm) D[v, 0.9] (μm) Example 2 2.56.7 15.7 Example 3 2.1 5.1 11.357 Example 4 15.4 55.1 135.9 Example 52.1 5.9 15.2 Example 6 2.0 5.3 12.4 Example 7 3.4 11.4 32.1 Example 81.3 2.8 5.6 Example 9 6.2 22.5 53.4

This experiment shows that the particle size distribution varies throughvariations in solvent composition.

Example 11: Particle Size Data Before and after Micronisation

Particles were micronized using a JetPharma MC150 (6 inch spiral jetmill) using the following conditions:

-   -   Feed rate: 15 g/min    -   Mill pressure: 3.5 bar    -   Venturi Pressure: 5.5 bar    -   Micronisation scale: 0.5 Kg.

The micronisation comparison of Examples 8 and 9 showing the impact ofingoing particle size on micronisation output is summarized in Table 3below:

TABLE 3 Ingoing particle size Post-micronisation particle size BatchD[v, 0.5] (μm) D[v, 0.5] (μm) Example 8 2.8 2.3 Example 9 22.5 4.0

Example 12: Product Recovery after Micronisation

An additional and significant advantage of the particles resulting fromthe process according to the present invention is the increased yield inmicronized fluticasone propionate due to lower loss of product in thejet milling chamber, compared to micronisation input obtained from aconventional anti-solvent process such as the one described inExample 1. Several batches crystallised by either conventionalanti-solvent techniques (as described in Example 1) or reverseanti-solvent techniques according to the present invention (as describedExamples 2-9) were micronized, and the results summarised on Table 4below show that the percentage of product collected after micronisationwas on average much higher for reverse anti-solvent product batches thanfor conventional anti-solvent ones. Additionally, a much lower portionof product was left in the mill chamber if the product had originatedfrom reverse anti-solvent.

TABLE 4 Summary of product recovery after micronisation for anti-solventand reverse anti-solvent batches. % batch left in % batchCrystallization technique mill chamber recovered Conventionalanti-solvent technique 10.6 53 Conventional anti-solvent technique 13.946.5 Conventional anti-solvent technique 5.5 35.6 Conventionalanti-solvent technique 8.5 59.2 Reverse anti-solvent according to 2.163.1 present invention Reverse anti-solvent according to 2.2 78.9present invention Reverse anti-solvent according to 3.7 43.7 presentinvention Reverse anti-solvent according to 1.0 63.1 present inventionReverse anti-solvent according to 1.0 81 present invention

1. A process for preparing fluticasone propionate as crystallinepolymorphic form 1, the process comprising: dissolving fluticasonepropionate in a solvent to form a solution, and then adding the solutionto a non-solvent, thereby causing fluticasone propionate to crystalliseout of the solution as crystalline form 1; wherein the solvent comprisesacetone and from 0% to 10% water, based on the volume of the solvent;and wherein the non-solvent comprises water and from 0% to 35% acetone,based on the volume of the non-solvent.
 2. A process according to claim1, wherein fluticasone propionate is dissolved in the solvent in anamount between 30 and 50 grams per litre of solvent.
 3. A processaccording to claim 1, wherein fluticasone propionate is dissolved in afirst defined volume of the solvent to form a solution, and the solutionis then added to a second defined volume of the non-solvent; a ratio ofthe first defined volume to the second defined volume being between1:0.65 and 1:1.35.
 4. A process according to claim 2, whereinfluticasone propionate is dissolved in a first defined volume of thesolvent to form a solution, and the solution is then added to a seconddefined volume of the non-solvent; a ratio of the first defined volumeto the second defined volume being between 1:0.65 and 1:1.35.
 5. Aprocess according to claim 1, wherein said adding the solution takesplace at a temperature between about 10° C. and about 40° C.
 6. Aprocess according to claim 1, wherein said adding the solution takesplace over a period of between about 10 minutes and about 6 hours.
 7. Aprocess according to claim 5, wherein said adding the solution takesplace over a period of between about 10 minutes and about 6 hours.
 8. Aprocess according to claim 1, wherein said adding the solution occursvia a pump in the form of pulsed aliquots.
 9. A process according toclaim 1, wherein said adding the solution occurs over a period ofbetween about 10 minutes and about 6 hours via a pump in the form ofpulsed aliquots.
 10. A process according to claim 1, wherein once thestep of adding the solution to the non-solvent is completed, a slurryforms and the slurry is stirred over a period of between 0 and about 12hours, followed by filtration of the slurry to recover fluticasonepropionate as crystalline form 1 and drying of the recovered fluticasonepropionate.
 11. A process according to claim 5, wherein once the step ofadding the solution to the non-solvent is completed, a slurry forms andthe slurry is stirred over a period of between 0 and about 12 hours,followed by filtration of the slurry to recover fluticasone propionateas crystalline form 1 and drying of the recovered fluticasonepropionate.
 12. A process according to claim 7, wherein once the step ofadding the solution to the non-solvent is completed, a slurry forms andthe slurry is stirred over a period of between 0 and about 12 hours,followed by filtration of the slurry to recover fluticasone propionateas crystalline form 1 and drying of the recovered fluticasonepropionate.
 13. A process according to claim 8, wherein once the step ofadding the solution to the non-solvent is completed, a slurry forms andthe slurry is stirred over a period of between 0 and about 12 hours,followed by filtration of the slurry to recover fluticasone propionateas crystalline form 1 and drying of the recovered fluticasonepropionate.
 14. Fluticasone propionate form 1, wherein said fluticasonepropionate form 1 is obtained by a process according to according toclaim 1, wherein said fluticasone propionate form 1 has a medianparticle size of between 5 microns and 35 microns.
 15. Fluticasonepropionate form 1, wherein said fluticasone propionate form 1 isobtained in the form of particles by a process according to according toclaim 1, wherein said particles do not exhibit agglomeration. 16.Fluticasone propionate form 1, wherein said fluticasone propionate form1 is obtained in the form of particles by a process according toaccording to claim 1, wherein said particles are between 5 and 200microns in length, and have a width of between 3 and 30 microns.